The Southern Pygmy Mouse is a small mouse whose back fur varies from reddish-brown to dark across its range. It has been found in grassy and shrubby places and eats grass seeds, nuts, and other plant foods.
Adults measure 10–13.5 cm in total length. Fur on the back ranges from dark reddish-brown and ochre to nearly black, while the underside is pale gray or whitish.
It has been found in tall grass and rocky places, and underground burrows were reported. Foods include nuts, bark, grass seeds, and leaves. The author thought it was active from daytime into dusk, while noting that behavioral observations were scarce.
An extinction-risk assessment has not been added yet.